Maths Year 6

1. Let us find the number of beads in this bag a
Then let us find the value of a in this equation a - 5 = 18
𝑎 − 5 𝑎=
≠
=18 18 + 5
𝑎 − 5 + 5 18

2. Let us find the number of beads in this bag a
Then let us find the value of a in this equation a + 5 = 18
𝑎 + 5 𝑎=
≠
=18 18 − 5
𝑎 + 5 − 5 18

3. 5 = 5 5 + 4 = 5 + 4
9 ≠ 5

4. The average (mean) of four numbers is 8, two of the numbers are 6, one of the numbers is
9, what is the fourth number a?
Average [(2*6) + 9 + a] = 8
Average [12+ 9 + a] = 8
Average [21+ a] = 8
There are four numbers, therefore: Average [21+ a] =
𝟐𝟏+𝒂
𝟒
𝟐𝟏+𝒂
𝟒
= 8
4 *
𝟐𝟏+𝒂
𝟒
= 4 * 8
21 + a = 32 Therefore: a = 11

5. The average (mean) of five numbers is 8. A sixth number is added and the new average
became 10. What the new added number a?
Average [8 + 8 + 8 + 8 + 8] = 8
Average [5 * 8]=8 Therefore:
𝟖 ∗𝟓
𝟓
= 8
A sixth number is added, and the new average became 10, therefore:
Average [8 + 8 + 8 + 8 + 8 + a] = 10 Average [(8*5) + a ] = 10
𝟒𝟎 + 𝒂
𝟔
= 10
6 *
𝟒𝟎 + 𝒂
𝟔
= 6 * 10
40 + a = 60 Therefore: a = 20

6. 𝟑
𝟖
𝟓
𝟏𝟐
𝟏𝟎
𝟐𝟒
𝟗
𝟐𝟒